Custom Konstrained values¶

Konstrained is the contract for custom feature values that are not built-in primitives or enums. Use it when the feature value is a real domain object and you still want JSON round-tripping through konditional-json.

Start with an object-backed value¶

Object-backed values are the most straightforward shape for custom payloads.

import io.amichne.konditional.core.types.Konstrained
import io.amichne.kontracts.dsl.of
import io.amichne.kontracts.dsl.schema

data class RetryPolicy(
    val maxAttempts: Int = 3,
    val backoffMs: Double = 1000.0,
    val enabled: Boolean = true,
    val mode: String = "exponential",
) : Konstrained.Object {
    val schema =
        schema {
            ::maxAttempts of { minimum = 1 }
            ::backoffMs of { minimum = 0.0 }
            ::enabled of { default = true }
            ::mode of { minLength = 1 }
        }
}

The schema is what lets the JSON layer reject malformed payloads instead of constructing a half-trusted value.

Use the value in a feature¶

Declare the feature with custom<T, C>(...) just like you would declare an enum or a boolean feature.

object CheckoutFlags : Namespace("checkout") {
    val retryPolicy by custom<RetryPolicy, Context>(
        default = RetryPolicy(),
    )
}

Other supported shapes¶

Konstrained also supports primitive-backed value classes, array-backed values, and adapted primitive encodings such as AsString or AsInt. Reach for those shapes when the wire form is a single primitive or a single list.

Next steps¶

If your custom values depend on a domain dimension like environment or tenant, the next guide shows how to model that dimension as an axis.

• Read the custom axes guide